2001g-489 2003f-649 antineoplasticagents cancer chemistry conservationofnaturalresources drugapproval economicaspects economics folklore harvesting herbalmedicine history kk5244 northwest pacific pacificyew paclitaxel phytogenic phytotherapy plantextracts politicalaspects qv11aa1g653s2001 qv269t23582003 research therapeuticuse treatment trees unitedstates utilization yew